Seminars

Plants are nature’s master chemists; they deploy complex networks of specialized metabolites to interact with other organisms and cope with environmental challenges. Among these metabolites, terpenes encompass the largest class with critical functions in plant development, chemical ecology and adaptation. These various terpenoid bioactivities also offer a rich source for medicinal, agricultural and other biotechnology applications. A deeper knowledge of the biosynthesis, diversity and distribution of plant terpenoids can guide the discovery of natural products and pathways, unveil their role in plant-environment interactions, and provide a toolbox for bioproduct manufacture. We established deep transcriptome resources for more than a dozen medicinal, food and bioenergy plants that produce common and unique terpenoids. By integrating a custom gene discovery platform with metabolite profiling and multi-gene co-expression analyses for efficient cross validation of enzyme functions, we identified numerous novel terpene synthases and cytochrome P450 monooxygenases, as key enzymes in generating terpenoid metabolic diversity. We will report on the discovery of unusual terpene synthases en route to new drug lead compounds, as well as previously unrecognized terpenoid pathways in the food and bioenergy crops maize and switchgrass that contribute to the defense against biotic and abiotic stressors. We show that terpenoid biosynthetic enzymes form modular pathway networks, where catalytically distinct enzyme modules may function in different combinations to enhance chemical diversity. Following nature’s lead, we combine protein and pathway engineering to develop proof-of-concept microbial and plant-based platforms for producing bioactive terpenoids via “Plug & Play” combinatorial expression of pathway genes from different species.